1. Field of the Invention
The present invention relates to a sputtering apparatus, and more particularly, to a sputtering apparatus configured to prevent damage to a container.
2. Description of the Related Art
When substrates for semiconductor wafers or liquid crystal panels are manufactured, they are subjected to various repeating treatment processes, such as thin film processing and etching. A sputtering apparatus is generally used for such thin film processing. A sputtering apparatus is an apparatus for forming thin film, for example, and is an indispensable component in the manufacturing of semiconductor devices and liquid crystal display devices (LCDs). In light of the complicated processes required for manufacturing large panels, and a need to increase manufacturing yields, robotic technology is being increasingly used for automating the operation of sputtering apparatuses.
FIG. 1 is a schematic view of a related art cluster-type sputtering apparatus. Referring to FIG. 1, a related art cluster-type sputtering apparatus includes a substrate retaining portion 108 for retaining a substrate 107 over a specified duration, and a sputtering portion 109 for sputtering the substrate 107 retained by the substrate retaining portion 108. The substrate retaining portion 108 includes a substrate retaining plate 110 that moves horizontally or vertically by means of a shaft 111.
A container 118 is provided at the front of the substrate retaining plate 110. The container 118 can be formed of quartz or pyrex, for example. Quartz and pyrex have to be handled carefully because they contain a large amount of glass, and are susceptible to damage from outside pressures.
A sheath heater 119 is provided at the rear of the substrate for controlling temperature. The sheath heater 119 may be installed within the substrate retaining plate 110.
The substrate 107 to be treated is placed on the container 118. In this case, heat generated by the sheath heater 119 can be transmitted to the substrate 107 through the container 118. The temperature of the container 118 must be uniformly maintained to form a uniform film on the substrate 107. Thus, the container 118 is made of an appropriately selected material.
A vacuum pump 117 is provided for discharging air and creating a vacuum in the sputtering apparatus. A discharge nozzle (not shown) is provided at the bottom of the substrate retaining plate 110 for discharging a gas, for example Ar gas.
The sputtering portion 109 includes a cathode 114 for supplying a negative voltage, a target 115 provided at the front of the cathode 114 for discharging a target material through collision created by positive ions of a gaseous plasma, and a magnet 116 provided at the rear of the cathode 114 for forming a magnetic field around the target 115 to generate more positive ions. A shield magnet 112 is provided along an inner surface of a main body 113 to separate the substrate retaining portion 108 from the sputtering portion 109.
During sputtering operation, the substrate 107 is positioned on the container 118. Then, the shaft 111 moves the substrate retaining plate 110 vertically, so that the substrate 107 faces the target 115. Next, Ar gas, for example, is discharged from the discharge nozzle. Then, plasma is generated by applying a high voltage. Here, ionic Ar+ ions collide with the target 115, and particles separated from the target 115 are deposited on the substrate 107.
As described above, the substrate 107 is positioned on the container 118. The container 118 usually has a diameter larger than that of the substrate 107. Thus, when the substrate 107 is positioned on the container 118, the container 118 is not covered entirely by the substrate 107. Thus, during plasma generation, particles from the target 115 adhere to uncovered portions of the surface of the container 118. After continued plasma generation, these particles from the target 115 peel off from the uncovered portions of the surface of the container 118. The target material that peels off becomes an impurity that adheres to and contaminates the substrate 107.
Moreover, the uncovered portions of the surface of the container 118 is easily damaged by the high-temperature plasma.
Therefore, in various sputtering apparatuses, the container 118 is replaced by a new container 118, or the container 118 is removed, thoroughly washed to discard the target material adhered onto the surface of the container 118, and then re-installed in the sputtering apparatus. When transporting the container 118 to be washed, careless handling can lead to damage of the container.
FIG. 2 is a plan view of the related art container of FIG. 1. Referring to FIG. 2, fixing holes 118a and 118b are provided on opposite sides of the container 118. The container 118 is fixed to the substrate 107 retaining plate 110 through these fixing holes 118a and 118b. 
The container 118 expands due to the heat generated by the high temperature plasma. The opposite sides of the container 118 are fixed to the substrate retaining plate 110, so that there is no freedom of movement for the container 118. As such, the container 118 is easily damaged from heat expansion.
As discussed above, the related art cluster-type sputtering apparatus may cause contamination of the substrate due to the adherence and subsequent peeling off of target material on exposed portions of the container. Moreover, the related art container can be easily damaged due to expansion caused by the high temperature plasma.